Damages of Skidder and Oxen Logging to Residual Trees in Uneven-Aged Mixed Forest

The negative influence of timber harvesting on the forest environment is reflected through damage to the residual trees, regeneration, and forest soil. Considering that skidding, a popular extraction method, can cause substantial and severe damage to the remaining stand, the aim of this research was to determine damage to residual trees during skidding by an LKT 81T cable skidder, including oxen bunching. The research was conducted in eastern Bosnia and Herzegovina, in an uneven-aged mixed fir (Abies alba Mill.) and spruce (Picea abies L.) forest with pine (Pinus sylvestris L.) on limestone soils. Tree felling was conducted using a Husqvarna 372 XP chainsaw. Extraction operations caused damage to 6.31% of the residual trees in the stand. The most damage was removed bark (65.34%) and occurred on the lower parts of the tree, the butt end (55.11%) and root collar (32.39%). The average size of the damage was 197.08 cm(2). A statistically significant correlation was found between the damage position and the diameter at the breast height (p < 0.05) and the damage position and damage size (p < 0.01) by Spearman correlation analysis. The conducted analysis by the chi-squared test showed that there is a statistically significant difference in the proportion of damage for trees with different distances to the nearest skid road (p = 0.0487), but the share of damaged trees did not decrease by increasing the distance from the skid road.

Automated summary

The negative impact of timber harvesting on the forest environment is evident in the damage caused to the remaining trees, regeneration, and forest soil. This study focused on assessing the damage to residual trees during skidding using an LKT 81T cable skidder, taking place in an uneven-aged mixed fir and spruce forest in eastern Bosnia and Herzegovina. The results revealed that extraction operations resulted in damage to 6.31% of the residual trees, with bark removal being the most common type of damage (65.34%), primarily occurring at the lower parts of the trees (butt end - 55.11% and root collar - 32.39%).